The present invention relates to a switching device and to a fault current circuit breaker. The present invention also relates to a method for functional testing of a first fault current circuit breaker without interruption of the power supply to a connected load.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Fault current circuit breakers have a testing device for testing the functionality of the respective fault current circuit breaker, i.e. triggering, in the event of a fault current. Because the respective fault current circuit breaker is triggered, the downstream partial networks and hence also all connected electrical devices are switched off. This is viewed by most uses of electrical systems as inconvenient, because individual settings are erased in many devices. Moreover, severe problems in many electrical systems may occur when they are switched off, because these electrical systems perform safety-related tasks or control technical processes, so that switching these systems off can lead to problems.
In switching processes where a load current is switched from one fault current circuit breaker to another fault current circuit breaker, a temporary presence of asymmetric potentials on at least one of the two fault current circuit breakers cannot be excluded. Such differences in the potential, however, can act on a fault current circuit breaker like an actually present fault current and thus accidentally trigger the fault current circuit breaker without the presence of a fault current. This may possibly prevent uninterrupted switching from one fault current circuit breaker to another fault current circuit breaker.
It would therefore be desirable and advantageous to obviate prior art shortcomings and to provide an improved switching device which supports functional testing of a fault current circuit breaker without requiring disconnection from the power grid.